Windows 11 Pro 25H2 – Bonjour 3.1.0.1 / mdnsNSP.dll – Code Integrity Event ID 3033

Windows 11 Pro 25H2 – Bonjour 3.1.0.1 / mdnsNSP.dll – Code Integrity Event ID 3033

Hello Apple Developer Community,

I am seeking technical assistance with a persistent Windows Code Integrity event involving Apple's Bonjour for Windows, specifically mdnsNSP.dll. PowerShell diagnostics, signature checks, service checks, Winsock inspection, and Event Viewer analysis have not yet established a permanent fix. I would appreciate guidance from Apple engineers or developers familiar with Bonjour, Winsock Name Space Providers, and Windows signing policies.

1. SYSTEM

• Windows 11 Pro 25H2, build 26200
• iTunes 12.10.11.2 (classic Windows desktop application)
• Bonjour 3.1.0.1
• Bonjour directory: C:\Program Files\Bonjour\
• Affected file: C:\Program Files\Bonjour\mdnsNSP.dll
• Reported DLL version: 3.1.0.1; reported date: August 12, 2015

iTunes manages a large local music library. The existing iTunes application, its library database, metadata, and media files must be preserved. I do not want to migrate to Apple Music or Apple TV.

2. ERROR AND EVIDENCE

Windows Event Viewer reports:

• Provider: Microsoft-Windows-CodeIntegrity
• Event ID: 3033
• Affected process: C:\Windows\System32\svchost.exe
• Referenced DLL: C:\Program Files\Bonjour\mdnsNSP.dll

The diagnostic message indicates that the DLL does not meet the Microsoft signing-level requirements of the affected process. Yet signature verification reports a valid Apple digital signature. I have not determined the precise policy requirement or root cause. A signing-level incompatibility with Windows 11 25H2 is a possibility, not an established finding. This event alone does not prove that Bonjour as a whole is broken or that the DLL has a security vulnerability.

3. FINDINGS AND CHECKS

• Bonjour service: startup type Automatic; status Running.
• mDNSResponder.exe is running. This does not prove that every Bonjour component works.
• mdnsNSP.dll: publisher Apple; digital signature reported Valid.
• Winsock catalog: two entries reference mdnsNSP.dll. Whether these are expected separate registrations is not yet established.
• Examined Bonjour components, versions, service and process status, digital signatures, Windows networking configuration, Winsock catalog, and Event Viewer using PowerShell and Windows tools.
• No permanent repair has been confirmed. No broad Winsock reset or speculative registry modification is desired.

4. QUESTIONS

1) Is Bonjour 3.1.0.1, especially mdnsNSP.dll, known to have a compatibility or signing-level issue on Windows 11 25H2?

2) Why might an Apple-signed DLL with a valid Authenticode signature not meet the signing-level requirements of the svchost.exe process attempting to load it? Which diagnostics identify the exact policy?

3) What is the latest Apple-supported Bonjour version for this Windows environment? Is there a supported repair or update path independent of classic iTunes?

4) Is it normal for mdnsNSP.dll to appear twice in the Winsock catalog? If so, why?

5) Can Bonjour be repaired or reinstalled without modifying iTunes 12.10.11.2 or its library, and without disrupting other Winsock providers or network services?

6) Would the full Event ID 3033 XML, DLL signature details, and relevant Winsock entries help Apple determine the root cause? I can share appropriately redacted diagnostics on request.

5. SECURITY AND PRESERVATION REQUIREMENTS

I am looking for a documented, targeted, reversible where possible, and lasting solution—not merely a way to silence Event ID 3033. Please do not recommend disabling Code Integrity, Memory Integrity, or other Windows protections. The repair must not introduce security risks or impair other applications, network providers, or Windows services. I want to retain iTunes 12.10.11.2 and the entire music library, and avoid reinstalling Windows or installing Apple Music/TV.

I am comfortable running specific PowerShell diagnostics and reporting results. Personal identifiers, addresses, and unredacted logs have intentionally been excluded from this public report.

Thank you for your technical guidance.

REFERENCES

Apple Bonjour:

https://developer.apple.com/bonjour/

Microsoft Windows Security:

https://support.microsoft.com/en-us/windows/security/windows-security/device-security-in-the-windows-security-app#bkmk_lsa-protection

Microsoft Learn (LSA protection / Code Integrity events):

https://learn.microsoft.com/en-us/windows-server/security/credentials-protection-and-management/configuring-additional-lsa-protection